Intumescent gap seals

ABSTRACT

An intumescent gap seal comprises at least one flexible resilient sealing member ( 7,8 ) adapted to span a gap ( 4 ) defined between adjacent parts of a building ( 5,6 ) and an intumescent member ( 9 ) which, in an unexpanded state, is narrower than the gap ( 4 ). The or each sealing member ( 7,8 ) may comprise a curved elongate member to ease installation. Such a sealing member ( 7,8 ) will tend to keep its resilience better, so that its draught proofing qualities are maintained and will be easier to install.

This invention relates to intumescent gap seals.

Such seals are provided in expansion joints of buildings. An expansion joint is where a gap is left in brickwork, concrete or other building material, to allow for expansion and contraction of the building material with temperature. An intumescent gap seal draughtproofs the gap, and has intumescent material which expands in the event of a fire so that the seal provides a physical barrier in the gap to stop the spread of fire through the gap.

One known intumescent gap seal, designed for interior use, is of rectangular cross-section, and comprises thin layers of intumescent material interleaved with thicker layers of plastics foam. When inserted in a gap, the foam, but not the intumescent material, is compressed when the gap is reduced by expansion of the building. The foam expands when the gap increases on contraction of the building. This seal has two disadvantages. The first is that it is quite bulky, and may be difficult to install, as it needs to be compressed along its length to fit in the gap. The second is that, with time, the foam tends to become rigid, and can no longer expand and contract efficiently, so that the draughtproofing suffers. This is especially noticeable at low temperatures, when the building contracts and the foam is required to expand.

According to the present invention, an intumescent gap seal comprises at least one flexible resilient sealing member adapted to span a gap defined between adjacent parts of a building, and an intumescent member which, in an unexpanded state, is narrower than the gap.

Providing a flexible resilient sealing member to span the whole gap, and an intumescent member which is smaller than the gap eases installation, as it is only the sealing member which needs to be compressed for installation, and its flexibility makes this relatively easy. Such a sealing member will also tend to keep its resilience better, so that its draughtproofing qualities are maintained.

Preferably, the or each sealing member comprises a curved elongate member, whose lateral edges engage with a respective building part. A central portion of the or each sealing member is preferably thicker than the lateral edges.

Preferably, the or each sealing member is arranged so that its concave side faces the outside of the gap. In the event of a fire, the concave face of the or the outer sealing member burns, but that sealing member tends to remain as a barrier to the fire while the intumescent member expands fully and forms a seal. The intumescent material is therefore protected initially from damage by smoke and ash being blown onto it.

The intumescent member is attached to the central portion of the or each sealing member. Conveniently, the intumescent member is an elongate strip of rectangular cross-section.

Preferably, two sealing members are provided, separated by the intumescent member. This has the advantage that, in the event of a fire, the two sealing members define barriers within which the intumescent material expands. The sealing members are arranged in the same orientation, that is, so that each curves in the same way. This eases installation. Naturally, in this case the intumescent member is attached to a convex side of one sealing member and a concave side of the other sealing member.

The sealing members are preferably of a plastics or rubber material. A particularly preferred material is EPDM, as it is durable and has the required resilience over a wide temperature range. However, any other suitable thermosetting or thermoplastic material may be used.

The intumescent member conveniently comprises a mixture of intumescing material and a carrier material. The intumescing material may be graphite, while the carrier material may be a plastics material. Where the carrier material is a plastics material this is preferably similar to or compatible with the material of the sealing members. Thus, if the sealing members are of EPDM, the carrier material is also EPDM.

The sealing member or members are preferably co-extruded with the intumescent member, as this simplifies the manufacturing process, while providing a firm attachment between the sealing and intumescent members.

An embodiment of the invention is illustrated, by way of example only, in the accompanying drawings, in which:

FIG. 1 is a side view of an intumescent gap seal; and

FIG. 2 is a cross-section along the line 2-2 of FIG. 1.

The intumescent gap seal 1 shown in the figures is adapted to fit in an expansion joint 2 (see FIG. 2) in a building 3. Expansion joints are gaps 4 left between adjacent building parts 5, 6, in brickwork or other building material, to allow for expansion and contraction of the building material with temperature. The intumescent gap seal 1 is inserted in the gap 4 to draughtproof the gap 4 in normal use. In the event of a fire, intumescent material forming part of the seal 1 expands, so that the seal 1 provides a physical barrier in the gap 4 to stop the spread of fire through the gap 4.

The seal 1 shown in the drawings comprises two flexible resilient sealing members 7, 8, each adapted to span the gap 4, and spaced apart by an intumescent member 9 which, in the unexpanded state shown, is narrower than the gap 4.

Each flexible resilient sealing member 7, 8 is of curved elongate form, having tapered lateral edges 10, 11 which each engage a respective building part 5, 6. A central portion 12 of each sealing member 7, 8 is slightly thickened, and has the intumescent member 9 attached to it. The sealing members 7, 8 are both oriented in the same way, so that the intumescent member 9 is attached to the convex side of the sealing member 7 and the concave side of the sealing member 8. The sealing members 7, 8 are extruded from EPDM, and then cured.

The intumescent member 9 comprises an elongate strip of substantially rectangular cross section. In its unexpanded state, it is considerably narrower than the gap 4, but in the event of a fire it will readily expand to fill the gap 4. The intumescent member is made of an intumescent material, such as graphite, together with a carrier material, in this case EPDM. The intumescent member 9 can then be co-extruded with the sealing members 7, 8, and cured with them. This simplifies manufacturing, while providing a good bond between the sealing members 7, 8 and the intumescent member 9.

Producing the seal 1 by extrusion means that relatively long lengths can be manufactured, from which appropriate lengths can be cut for installation.

The gap seal 1 is in fact designed for interior use, although it could be used outside, as EPDM is weatherproof.

In use, a suitable length of seal 1 is cut, and it is then inserted into the gap 4 so that the concave sides of the sealing members 7, 8 face the outside of the gap. It is easy to insert, as the lateral edges 10, 11 deflect resiliently. The edges 10, 11 then seal against the respective building parts 5, 6 to provide draughtproofing. The edges 10, 11 will remain in contact with the building parts 5, 6 as the building expands and contracts, due to the resilience of the sealing members 7, 8.

In the event of a fire, the outer sealing member 7 will start to burn, and the heat will be transmitted through to the intumescent member 9. When this reaches its threshold temperature (about 170° C.) it will expand. It has been found that, even though the outer sealing member 7 is burning, it will tend to stay in place and create a barrier for the intumescent material. Similarly, the inner sealing member 8 will also create a barrier, so that the expanded intumescent material tends to be confined between the two sealing members. This provides at least partial control of the expanded intumescent material, which is advantageous, as it is retained in the gap 4, rather than expanding outside it, and falling out. The physical barrier provided by the intumescent material is therefore enhanced.

In the initial stages of a fire, the outer sealing member 7 also protects the intumescent material while it is expanding, from damage by smoke, gas and ash which may be blown onto it. The intumescent material will normally be fully expanded and formed as a seal before the outer sealing member 7 burns away and exposes it.

In a modification (not shown) the sealing members 7, 8 may be of a different shape, for example the edges 10, 11 may have more than one sealing face. In other modifications (not shown) only one sealing member may be provided, or more than two sealing members may be provided. The intumescent member 9 may also be of a different shape.

While in the embodiment described the sealing members 7, 8 and the carrier material are of EPDM, other materials (whether thermoplastic or thermosetting plastics or rubber materials) could be used. It would also be possible for the sealing members 7, 8 to be joined by a hollow tube, in which a strip of intumescent material could be inserted. 

1. An intumescent gap seal adapted to span a gap defined between adjacent parts of a building, comprising at least one flexible resilient sealing member adapted to span said gap, and an intumescent member which, in an unexpanded state, is narrower than said gap.
 2. A seal as claimed in claim 1, wherein said at least one sealing member comprises a curved elongate member having lateral edges engaging a respective building part of the adjacent parts of the building.
 3. A seal as claimed in claim 1, in which a central portion of said at least one flexible resilient sealing member is thicker than said lateral edges.
 4. A seal as claimed in claim 2, in which said at least one flexible resilient sealing member is arranged so that a concave side faces the outside of the gap defined between the adjacent parts of the building.
 5. A seal as claimed in claim 1, in which said intumescent member is attached to a central porition of said at least one flexible resilient sealing member.
 6. A seal as claimed in claim 1, in which said intumescent member is an elongate strip of rectangular cross-section.
 7. A seal as claimed in claim 1, in which two of said at least one flexible resilient sealing members are provided, separated by said intumescent member.
 8. A seal as claimed in claim 2, in which two flexible resilient sealing members are provided, separated by said intumescent member and arranged in the same orientation so that each curves in the same way.
 9. A seal as claimed in claim 8, in which said intumescent member is attached to a convex side of one of said sealing members and a concave side of the other of said sealing members.
 10. A seal as claimed in claim 1, in which the said sealing members are of plastics.
 11. A seal as claimed in claim 1, in which said sealing members are of rubber material.
 12. A seal as claimed in claim 1 in which said sealing members are of EPDM.
 13. A seal as claimed in claim 1, in which said intumescent member comprises a mixture of intumescing material and a carrier material.
 14. A seal as claimed in claim 13, in which said intumescing material is graphite.
 15. A seal as claimed in claim 13, in which said carrier material is a plastics material.
 16. A seal as claimed in claim 15, in which said plastics material is compatible with the material of said at least one flexible resilient sealing member.
 17. A seal as claimed in claim 15, in which said carrier material is the same as the material of said at least one flexible resilient sealing member.
 18. A seal as claimed in claim 1, in which said at least one flexible resilient sealing member is co-extruded with said intumescent member. 